The UK Government has expressed its "disappointment" at the mass executions carried out by Saudi Arabia which have triggered unrest in the region and led to a breakdown in diplomatic relations between Riyadh and Tehran.
There has been an international outcry over the execution of 47 prisoners including prominent Shiite cleric Sheikh Nimr al-Nimr, who has been a leading critic of the Riyadh authorities.
Saudi Arabia announced the execution of Sheikh al-Nimr on Saturday, sparking a wave of protests and the storming of the country's embassy in Shiite powerhouse Iran.
Riyadh responded by announcing it would sever diplomatic ties, with staff from the Iranian mission given 48 hours to leave and Saudi counterparts recalled home from Tehran.
With the threat of further sectarian violence triggered by the executions in predominantly Sunni Saudi Arabia, the UK called for calm in the region.
Foreign Office minister Tobias Ellwood said: "I am deeply disturbed by the escalation in tensions in the last 24 hours in the Middle East.
"The UK is firmly opposed to the death penalty. We have stressed this to the Saudi authorities and also expressed our disappointment at the mass executions."
The Middle East minister said he expected the kingdom's government not to carry out the death sentence imposed on the cleric's nephew Ali al-Nimr, who was just 17 when he was told he faced crucifixion over his role in the Arab Spring protests in 2012.
Mr Ellwood said: "We have discussed with the authorities in Riyadh, and expect that Ali Al-Nimr and others who were convicted as juveniles will not be executed. The UK will continue to raise these cases with the Saudi authorities.
"We are deeply concerned to hear of the attack yesterday on the Saudi embassy in Tehran. It is essential that diplomatic missions are properly protected and respected.
"There are those who will wish to exploit the situation and raise sectarian tensions higher. This would be against the wishes of the vast majority of those in the region. I urge all parties in the region to show restraint and responsibility."
Earlier, Treasury minister David Gauke said capital punishment was "wrong" and the ties between the UK and Riyadh meant "we can tell them what we think".
Treasury financial secretary Mr Gauke told Sky News' Murnaghan programme: "Clearly it is a very worrying development and we oppose capital punishment in this way, we think that that is wrong."
But he added: "When it comes to protecting British people, the Prime Minister has made it clear that intelligence from Saudi Arabia has helped save lives and protect people in the UK ... We have a relationship with Saudi Arabia where we are able to speak candidly to them, where these issues are raised on a regular basis by the Foreign Secretary and the Prime Minister and our representatives in Riyadh.
"We are able to have that relationship where we can tell them what we think and clearly it is a worrying development, what we have heard from Saudi Arabia in the last few days."
Ministers had come under pressure to speak out following the executions on Saturday, which placed the UK's economic and diplomatic links with the Arab kingdom under further scrutiny.
Shadow foreign secretary Hilary Benn described the executions as "profoundly wrong" and Liberal Democrat leader Tim Farron urged David Cameron to speak out against the Saudi regime's actions.